1. Field of the Invention
This invention relates to novel hindered amine stabilizers. More specifically, this invention is directed to the synthesis of hindered amines by base-induced condensation of a primary amine with an .alpha.-halo-acetamide.
2. Description of the Prior Art
The increasing use of polymers in the place of the more traditional types of structural materials, (e.g. wood, metals, etc.) has necessitated the compounding of such polymers with a variety of stabilizers in order to enhance their ability to withstand prolonged exposure to a variety of degradative forces. Degradation of such environmentally sensitive polymers can be caused by exposure to light, heat and/or air. Such degradation is usually manifest by either a partial or total loss of structural integrity, changes in light transmission properties, changes in color, loss or reduction in flexibility and/or resiliency, or any combination of the above phenomenon. As will be appreciated, the stabilizers which are used in conjunction with the above polymeric materials, in addition to providing protection against such degradative forces, must also be compatible with the aesthetic properties of the polymeric article formed from such materials and be effective at low concentrations. The economics of the marketplace dictate that these stabilizers be relatively inexpensive and capable of preparation from readily available starting materials by simple and straightforward synthesis techniques.
The prior art is replete with both patents and technical articles describing various stabilizers suitable for use in structural/engineering plastics and in various synthetic fibers. The hindered amine stabilizers are prominently mentioned as suitable in the stabilization of such materials against ultraviolet light degradation. Illustrative of these hindered amines are the decahydroquinolines disclosed in U.S. Pat. Nos. 3,919,234; 3,920,659; 3,928,330; 4,069,195; and 4,073,770; the 1,5-diazacycloalkan-2-ones disclosed in U.S. Pat. No. 4,207,228; and, the 1,4-diazacycloalkan-2-ones disclosed in U.S. Pat. Nos. 4,167,512 and 4,240,961. These hindered amine stabilizers can be prepared in various ways and from various materials.
The preparation of the U.V. stabilizers disclosed in U.S. Pat. Nos. 4,240,961 and 4,190,571 is reportedly achieved by phase transfer catalyzed reaction of certain appropriate starting materials. Phase transfer catalysis initiated synthesis is also reportedly effective in the synthesis of other types or stabilizer; namely, the synthesis of antioxidants and compounds which enhance a polymer's resistance to thermal degradation.
The first disclosure relating to the phase transfer catalyzed synthesis of this latter class of stabilizers is described in copending patent application Ser. No. 916,639 filed June 19, 1978, now U.S. Pat. No. 4,310,429. The compounds are prepared by a reaction of aniline, and its para-substituted derivatives, with chloroform, acetone and sodium hydroxide in the presence of a phase transfer catalyst.
The synthesis proceeds by the reaction of chloroform with base thereby generating a trichloromethide ion which can subsequently combine with the ketone (or aldehyde) forming an oxirane intermediate. This intermediate combines with the aniline, or its para-substituted derivatives, and optionally, with another primary amine yielding the desired reaction product.